1. Field of the Invention
The present invention relates to a control device/method for prohibiting downshifting of a vehicular manually shifted simple transmission, or the mainsection of a compound transmission, when an attempted shift into or a shift into the inhibited ratio(s) would result in unacceptable conditions such as probable excessive synchronous wear or burn-out and/or overspeeding of the vehicle engine.
More particularly, the present invention relates to a control for simple or compound manually shifted vehicular transmissions, particularly synchronized transmissions, which will prohibit or inhibit shift lever selection of a ratio or ratios which, under sensed vehicle conditions, such as vehicle speed, if engaged or attempted to be engaged, will result in unacceptable conditions such as excessive synchronizer wear, synchronizer burn-out and/or engine overspeeding.
2. Description of the Prior Art
Prior art devices exist for warning against and/or prohibiting or inhibiting operator attempts to manually engage a transmission ratio which, if engaged, will overspeed the engine and/or have other undesirable results. Such devices typically involve warning devices which provide a visual and/or audible warning if an attempt is made to engage an unacceptable ratio or inhibit fuel to the engine to govern/reduce vehicle speed.
The prior art devices were not totally satisfactory, as the vehicle operator may not react properly or rapidly enough to the alarm and/or the decrease in fueling may not result in a sufficiently rapid manner to prevent the undesirable consequences of engaging or attempting to engage an unacceptable transmission ratio.
In a heavy duty manually shifted synchronized transmission utilizing effective, powerful synchronizers, the synchronizers themselves, by virtue of being well designed and capable of bringing jaw clutch members and related components quickly to synchronous speed, are open to driver abuse, which often leads to damage or premature wear/failure of the synchronizers and/or damage to the vehicle power train, such as the engine.